The official American Petroleum Institute website (api.org) is a good starting point. API often provides its publications for sale on its website. You can search for Specification 6A.
: You can purchase the standard or subscribe for organization-wide access through the API Webstore API Compass platform Public Access api specification 6a 21st edition pdf link
High-Pressure High-Temperature (HPHT) wells are becoming common. The official American Petroleum Institute website (api
The requirements for proving a design works (PR2 testing) have been tweaked. api specification 6a 21st edition pdf link
You will find websites (Scribd, DocPlayer, various engineering forums) offering a "free PDF link." Here is why: